774 FXUS61 KALY 311141 AFDALY AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 741 AM EDT SAT AUG 31 2013 .SYNOPSIS... A WARM AND HUMID AIR MASS WILL IMPACT EASTERN NEW YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A SERIES OF WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY NEAR THE SAINT LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND THUNDERSTORMS TODAY WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 655 AM EDT...THE LAST FULL DAY OF AUGUST AND METEOROLOGICAL SUMMER BEGAN WITH SHOWERS AND SCT THUNDERSTORMS ACROSS PORTIONS OF THE ALY FCST AREA...ESPECIALLY FROM THE NRN CATSKILLS...CAPITAL REGION AND SRN VT NORTHWARD. A COUPLE OF WEAK SFC LOWS ARE MOVING ALONG A STATIONARY FRONT NEAR THE ST LAWRENCE RIVER VALLEY AND ERN GREAT LAKES THIS MORNING. LOW-LEVEL CONVERGENCE WITH THE SFC LOWS HAS HELPED THE SHOWERS AND THUNDERSTORMS BE THE MOST PERSISTENT IN THE MOHAWK RIVER VALLEY...SRN DACKS...AND THE LAKE GEORGE SARATOGA REGION. THIS ACTIVITY WILL CONTINUE TO WANE EARLY THIS MORNING...AND A BRIEF LOW WILL OCCUR TOWARDS NOONTIME. THE POPS WERE RETRENDED THIS MORNING BASED ON THE RADAR TRENDS. A MAJORITY OF THE GUIDANCE SHOWS ANOTHER WEAK RIPPLE OF LOW PRESSURE MOVING ALONG THE BOUNDARY IN THE AFTERNOON WITH A MID LEVEL SHORT-WAVE IN THE W/SW FLOW ALOFT. IT IS QUESTIONABLE IF ANY SIGNIFICANT HEATING WILL OCCUR EXCEPT PERHAPS ALONG THE SRN TIER OF THE FCST AREA /MID HUDSON VALLEY AND NW CT/. THE 0-6 KM DEEP SHEAR IS WEAK WITH WEAK MID LEVEL LAPSE RATES ALOFT...SO WIDESPREAD SEVERE CONVECTION IS NOT ANTICIPATED DESPITE SBCAPE VALUES OF 1000-2000 J/KG ACCORDING THE NAM/GFS. H850 THETA-E VALUES WILL BE GENERALLY IN THE 335-340K RANGE. THE PWATS WILL BE IN THE 1.25-1.75 INCH RANGE /1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL/...SO LOCALLY HVY RAINFALL WILL BE THE MAIN ISSUE. THE ENHANCED WORDING WAS PUT IN THE GRIDS...AND WILL BE MENTIONED IN THE HWO. IF THE HIGHER CAPE VALUES ARE REALIZED...AN ISOLATED WET MICROBURST MAY BE POSSIBLE. THE MAIN THREAT CONTINUES TO BE HEAVY RAINFALL. THE HIGHEST POPS IN THE LIKELY RANGE WERE USED ACROSS THE NRN HALF OF THE FCST AREA. THE 07Z 3KM HRRR COLUMN REF PRODUCT SHOWS DISCRETE CONVECTIVE ELEMENTS FORMING INTO A LINE OVER THE HUDSON RIVER VALLEY IN THE MID AFTERNOON. IN A WEAK SHEAR ENVIRONMENT THIS APPEARS TO BE OFF SOME...BUT WILL HAVE TO BE MONITORED. LATER RUNS HAVE SHOWN LESS SIGNIFICANT COVERAGE AND ORGANIZATION. THE SFC DEWPTS WILL REMAIN IN THE 60S WITH PERHAPS SOME SPOTTY LOWER 70S OVER THE SRN TIER. THE AIR MASS WILL BE STICKY FOR THE LAST DAY OF AUGUST. MINIMAL HEATING SHOULD ALLOW FOR U70S TO L80S IN THE VALLEYS...WITH 70S OVER THE HILLS AND MTNS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... TONIGHT...THE SHOWERS AND THUNDERSTORMS SHOULD DIMINISH IN THE EARLY EVENING WITH THE WEAK SFC WAVE MOVING EAST/NORTHEAST OF THE REGION...AND THE MID LEVEL SHORT-WAVE PASSING DOWNSTREAM. THE FRONTAL BOUNDARY MAY MOVE OVER THE NRN HALF OF THE FCST AREA AND FALL APART. THE POPS WERE LOWERED TO SLIGHT CHC VALUES AFTER MIDNIGHT. IT WILL REMAIN VERY HUMID WITH LOWS IN THE MID AND U60S OVER MOST OF THE REGION...EXCEPT OVER THE MTNS. SUNDAY...THE ENTIRE DAY SHOULD NOT BE A WASHOUT WITH AN AMPLIFYING UPPER LEVEL TROUGH OVER ONTARIO AND THE GREAT LAKES REGION. THE MID LEVEL FLOW WILL BECOME SOUTHWESTERLY OVER NY AND NEW ENGLAND WITH WEAK RIDGING ALOFT. THEIR ARE NOT ANY REAL ROBUST SYNOPTIC TRIGGER MECHANISMS DURING THE DAY. AIR MASS OR DIFFERENTIAL HEATING THUNDERSTORMS ARE POSSIBLE. A SLIGHT TO LOW CHANCE OF SHOWERS AND THUNDERSTORMS WAS INCLUDED IN THE GRIDS. H850 TEMPS INCREASE TO +16C TO +17C WITH PARTLY SUNNY CONDITIONS. MAX TEMPS WILL RUN ABOUT 5-10 DEGREES ABOVE NORMAL TO OPEN SEPT. SUNDAY NIGHT INTO LABOR DAY...A LARGE TROUGH OF LOW PRESSURE IMPACTS THE REGION. SEVERAL MID LEVEL SHORT-WAVES ROTATING AROUND THE CLOSED LOW SOUTH OF JAMES BAY WILL YIELD UNSETTLED WX DURING THIS TIME FRAME. IT IS DIFFICULT TO DETERMINE IF ANY ROBUST SFC HEATING WILL OCCUR AT THIS TIME. THE STRONG SYNOPTIC LIFT WITH THE TROUGH WILL LIKELY YIELD PERIODS OF SHOWERS AND SCT THUNDERSTORMS. SOME HVY RAINFALL LOOKS LIKE A GOOD BET. THE QG LIFT INCREASES LABOR DAY AFTERNOON...AS THE NRN HALF OF THE FCST AREA GETS NEAR THE RIGHT ENTRANCE REGION OF A H250 JET STREAK WITH STRONG UPPER LEVEL DIVERGENCE ALOFT. PWATS CONTINUE ABOVE NORMAL FOR EARLY SEPT. LIKELY POPS WERE CONTINUED ON MONDAY. THE COOLER NAM MOS TEMPS WERE ALSO FOLLOWED CLOSELY WITH THE AMOUNT OF CLOUD COVER AND NUMEROUS SHOWERS EXPECTED. MAX TEMPS WILL BE HARD PRESSED TO GET OUT OF THE 70S WITH PERHAPS SOME 80F READINGS FROM THE CAPITAL REGION SOUTH IN THE MID HUDSON VALLEY. MONDAY NIGHT...LOW AND MID LEVEL HEIGHTS CONTINUE TO FALL...AS THE TROUGH OF LOW PRESSURE AND ITS ASSOCIATED COLD FRONT MIGRATE EAST OF THE REGION. A CHC OF SHOWERS WAS KEPT IN MOST OF THE OVERNIGHT. LOW LEVEL COLD ADVECTION IS EXPECTED WITH TEMPS FALLING INTO THE 50S OVER THE MTNS WITH LOWER TO MID 60S IN THE VALLEYS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... COOLER AND LESS ACTIVITY WEATHER AS WE HEAD THROUGH THE FIRST WEEK OF SEPTEMBER. THE MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN WITH THE NORTHEAST REMAINING UNDER A TROUGH AND THE RIDGE HOLDING ON OVER THE PLAIN STATES. A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION. THE FIRST ONE IS EXPECTED TO MOVE OFF TO OUR EAST ON TUESDAY WITH SOME LINGERING SHOWERS POSSIBLE MAINLY DURING THE MORNING. A PLEASANT DAY EXPECTED WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLE WARM TEMPERATURES. A SECONDARY COLD FRONT IS EXPECTED TO MOVE THROUGH THURSDAY WITH ISOLATED SHOWERS. A MORE AUTUMN-LIKE AIRMASS WILL BE USHERED IN AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE OF THE FRONT TO CLOSE OUT THE WEEK. TEMPERATURES THURSDAY AND FRIDAY ARE ANTICIPATED TO RUN ABOUT 5 DEGREES BELOW NORMAL. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... SOME SHOWERS CONTINUE TO MOVE EASTERLY ACROSS THE FORECAST AREA EARLY THIS MORNING IN ASSOCIATION WITH A PASSING SHORT WAVE TROUGH AND WEAK SURFACE LOW MOVING INTO THE SAINT LAWRENCE RIVER VALLEY. EXPECT A LULL IS THE PRECIPITATION FOR A BIT THIS MORNING AS THE SHORT WAVE TROUGH MOVES OFF TO THE EAST. HOWEVER...CHANCES FOR CONVECTION WILL INCREASE AS HEAD INTO THE AFTERNOON AS THE SURFACE LOW PASSES TO OUR NORTH AND ANOTHER SHORT WAVE TROUGH APPROACHES. WITH THE HELP OF DIURNAL HEATING AND INCREASED INSTABILITY THERE WILL BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS. DO NOT HAVE CONFIDENCE TO TIME THUNDERSTORMS AT INDIVIDUAL TAF SITES SO HAVE RUN WITH A TEMPO GROUP FOR SHOWERS TO HIGHLIGHT MOST LIKELY TIME FOR CONVECTION TO OCCUR. ALTHOUGH LOW VSBYS/CIGS ARE ALLOWING FOR OCCASIONAL IFR AND MVFR CONDITIONS EARLY THIS MORNING...AN IMPROVEMENT TO VFR CONDITIONS IS EXPECTED BY LATE THIS MORNING. MVFR WITH BRIEF IFR CONDITIONS ARE EXPECTED WITH ANY CONVECTION THAT IMPACTS TAF SITES TODAY. MVFR/IFR FOG/CIGS ARE EXPECTED TO DEVELOP TONIGHT...ESPECIALLY WHERE IT RAINS. OUTLOOK... SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA. MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUESDAY: LOW OPERATIONAL IMPACT. CHANCE OF SHRA. TUESDAY NIGHT-WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL. A SERIES OF WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY NEAR THE SAINT LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND THUNDERSTORMS TODAY WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION. THE RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 85 PERCENT THIS AFTERNOON...AND RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING. HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT 5 TO 15 MPH TODAY AND TOMORROW... AND BECOME LIGHT TO CALM TONIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY WEEKEND. SOME WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE AN ISOLATED FLASH FLOOD DURING THE HOLIDAY WEEKEND. RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN WHILE OTHERS REMAIN DRY. SOME AREAS NORTH OF THE CAPITAL REGION HAVE RECEIVED A HALF AN INCH TO AN INCH OF RAINFALL THIS MORNING. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...IAA AVIATION...IAA/FRUGIS FIRE WEATHER...WASULA HYDROLOGY...SND/WASULA